verbatimtex
%&latex
\documentclass{article}
\usepackage[LGR,T1]{fontenc}
\usepackage[greek,frenchb]{babel}
\usepackage[latin1]{inputenc}
\begin{document}
etex
%%
input courbescp;
beginfig(1);
  depart((0,0),(7,7),(3,3),1,1);
  grille(0.5);
  axes;
  graduationx(btex 1 etex);
  graduationy(btex 1 etex);
  draw courbe1(-4,4,100,0.5*x) withcolor bleu;
  draw courbe2(-2,1,100,-3*x) withcolor rouge;
  labelise1(btex $y=0,5x$ etex,0.85);
  labelise2(btex $y=-3x$ etex,0.8);
  marquepoint(placepoint(1,0.5));
  marquepoint(placepoint(-1,3));
  draw Projection(placepoint(1,0.5));
  draw Projection(placepoint(-1,3));
endfig;
beginfig(2);
  depart((0,0),(7,7),(3,3),1,1);
  grille(0.5);
  axes;
  graduationx(btex 1 etex);
  graduationy(btex 1 etex);
  draw courbe1(-3,4,100,0.5*x-2) withcolor bleu;
  labelise1(btex $y=0,5x-2$ etex,0.25);
  draw courbe2(0,2.5,100,-3*x+4) withcolor rouge;
  labelise2(btex $y=-3x+4$ etex,0.2);
  draw courbe3(-4,4,100,0.5*x) dashed evenly;
  labelise3(btex $y=0,5x$ etex,0.85);
  draw courbe4(-4,4,100,-3*x) dashed evenly;
  labelise4(btex $y=-3x$ etex,0.4);
  marquepoint(placepoint(0,-2));
  marquepoint(placepoint(0,4));
  marquepoint(placepoint(1,-1.5));
  marquepoint(placepoint(2,-2));
  draw Projection(placepoint(1,-1.5));
  draw Projection(placepoint(2,-2));
endfig;
beginfig(3);
  depart((0,0),(10,8.5),(1,1),1,1);
  millimetrepourcourbe orange;
  axes;
  graduationx(btex 20 etex);
  graduationy(btex 1,5 etex);
  legendex(btex durée etex);
  legendey(btex Prix en \textgreek{\euro} etex);
  draw courbe1(0,12,100,0.12*x*20/1.5) withcolor violet;
  draw courbe2(0,12,100,(4.8+0.04*x*20)/1.5) withcolor rouge;
  draw courbe3(0,12,100,10/1.5) withcolor bleu;
  labelise1(btex $y=0,12x$ etex,0.10);
  labelise2(btex $y=0,04x+4,8$ etex,0.1);
  labelise3(btex $y=10$ etex,0.1);
  draw paraver(4.5) dashed evenly;
  marquepoint(paraver(4.5) intersectionpoint Cb1);
  marquepoint(paraver(4.5) intersectionpoint Cb2);
  marquepoint(paraver(4.5) intersectionpoint Cb3);
  marquepoint(Cb2 intersectionpoint Cb1);
  marquepoint(Cb3 intersectionpoint Cb2);
  draw Projectiona(placepoint(3,4.6));
  draw Projectiona(placepoint(6.5,10/1.5));
  label.bot(btex $90$ etex,placepoint(4.5,0));
  label.bot(btex $60$ etex,placepoint(3,0));
  label.bot(btex $130$ etex,placepoint(6.5,0));
  
  
endfig;
end